Insulator



Dec. l5, 1931. y A, O. AUSTIN 1,836,743

INSULATOR Filed sept. 14, 1928 2 sheets-sheet 1 .IN VEN TOR A TTORNE YDec. l5, 1931.

A. o. AUSTIN 1,836,743

INSULATOR Filed Sept. 14, 1928 2 sheets-sheet 2 A TT ORNE Y PatentedDec. 15, 1931 UNITED STATES PATENT OFFICE .ARTHUR O. AUSTIN, OF NEARBARBERTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 THE OHIO BRASSCOMIANY, OF MANSFIELD, OHIO, A CORPORATION OF' NEW JERSEY INSULATORApplication led September 14, 1928.

This invention relates to electrical insulators and has for one of itsobjects the provision of an insulator having high mechanical stress andone which will withstand high electrical surges produced by atmosphericdisturbances and, at the same time, will not be injured by leakagecurrents under normal operating voltages.

A further object is to provide an insulator having a tension memberequipped with a weather jacket and economical means for insuring a tightseal between the weather jacket and the tension member. Other objectsand advantages will appear from the following description.

The invention is exemplified in the combination and arrangement of partsshown in the accompanying drawings and described in the followingspecification and it is more particularly pointed out in the appendedclaims.

In the drawings:

Fig. l is a. fragmentary elevation with parts in section showing oneembodiment of the present invention.

Fig. 2 is a transverse section on line 2-2 of Fig. 1.

Fig. 3 is an elevation on a somewhat smaller scale than 1 showing bothends of an insulator constructed according to the present invention.

Fig, 4 is an elevation at right angles to Fig. 3.

Fig. 5 is a view similar to Fig. 1 showing a somewhat modied form of theinvention.

Fig. 6 is a section on line 6 6 of Fig. 5.

Fig. 7 is a view similar to Fig. 1 showing another modification of theinvention.

Fig. 8 is a section on line 8-8 of Fig. 7.

Fig. 9 is an elevation on a somewhat smaller scale than Fig. 7 showingthe insulator of Fig. 7 but having a slightly modified device forsecuring the expansion chamber in place.

Fig. 1() is a view at right angles to Fig. 9.

In electrical work, such as the insulation Serial No. 305,975.

of any high tension transmission lines and railway systems, considerablediiiculty is encountered in obtaining an insulator of high mechanicalstrength and one which will withstand high electrical surges produced bylightning and, at the same time, provide for leakage currents under thenormal operating voltage. This is particularly true in the insulation ofrailway systems where the insulators are likely to be subject to smokeor dirt from locomotives or in locations where there is a considerableaccumulation of conducting material.

In many cases, insulators made of wood or fibre will operatesatisfactorily. If, however, the leakage current becomes too heavy, thesurface is likely to burn, destroying the insulating properties of theinsulator. In the past, improved insulators having wood, fibre, or othersimilar tension members have been protected by an insulating sleeve suchas porcelain or glass which will withstand leakage current withoutcarbonizing. While these insulators have been very successful, theircost is rather high when considered for guy insulators or for theinsulation of lower voltage catenary systems. In the latter, itfrequently develops that considerable insulation is needed, even thoughthe voltage is not high, to withstand the rather severe conditionsproduced by smoke and conducting material and it is also necessary inmany cases to provide an insulator of good length so that birds, cats orsquirrels will not readily shortcircuit the insulator.

For many installations, it is highy desirable to produce insulators ofgreat strength but of small radial dimensions such as those used forsectionalizing purposes or in places of restricted clearance, as underbridges. The present invention is an improvement on an insulator shownin my previous Patent, Number 1,497,319, June 10, 1924, and makes itpossible to provide an insulator which will withstand very severeelectrical conditions and at much lower cost.

In the form of the invention shown in Fig. 1, the tension member 10,which is usually 5 of wood, is provided with a self-tightening grip heador holding member 11 similar to those shown in my previous patent,referred to above, but somewhat simpied. The tension member is slottedat 12 forming wood 10 friction plates and metal friction plates 13 areinserted in the slots 12. Wedge shaped Vgripping plates 14 are disposedat opposite sides of the tension member 10 and a bolt 15 extends throughthe member 10, friction 15 lates 13 and wedge plates 14. Straps or Ears16 engage the outer faces of the wedge members 14 and have openingstherein for the bolt 15. The bars 16 having portions thereof inclined tolit the outer inclined faces of the wedge members 14 and thus formclamping plates for clamping the wedge members 14 against the surface ofthe member 10 and for clamping the friction plates of the member 10against the friction plates 13. The wedge plates may have depressionsfor the straps 16 and lugs 17 for overlapping the edges of the member tolocate the parts relative to one another. The ends of the bolt 15 arepreferably bent to bring the head and nut squarely against the outersurface of the bars 16.

The openings in the bars 16 and plates 1-3 for the bolt 15 preferablylit the bolt closely while clearance is permitted about the bolt in themembers 10 and 14 so that the stress of the load is transmitted throughfriction of the metal parts upon the wood. The wedging action betweenthe bars 16 and wedge members 14 under the stress of the load, tends todraw the wedging members more tightly between the bars 16 and stressmember 10,

thus acting to tighten the grip on the member 10 and automaticallycompensating for any loosening of the joint caused by shrinkage of thewood or other causes.

The tension member 10 is provided with an insulating sleeve 18 composedof porcelain or other suitableinsulating material. This member 18 isprovided with a flange or gripping member 19 which is cemented orclamped to the insulating acket 18.` In the assembly of the insulator,the insulating sleeve 18 is slipped over the tension member 10 beforeone of the self-tightening heads 11 is attached.

After the sleeve 18, with its flange 19, is slipped over the tensionmember 10, a ring or collar 20 composed of rubber, cork or otheryielding material. is placed in a gland at the end of the sleeve 18. Atightening flange 21 G0 is then slipped over the member 10 and securedin place by bolts 22.

When the clamping member 21 is tightened, the packing material 2O willbe deformed so that tight contact will be made between the C5 packingmaterial, the tension member 10 and the sleeve 18, making a perfectlytight joint. After vone end is tightened, the intervening space betweenthe sleeve 18 and the tension member 1() may be filled with aninsulating compound 23 to prevent the entrance of wa-` ter or othermaterial, even though the packing gland may become loose. Since thesurface of the member 10, protected by the sleeve 12, will always have ahigh resistance compared to the outer surface of the sleeve 18, anyleakage of current will take place over the sleeve 18. Since thismaterial will not carbonize, the insulator will withstand very severeconditions which might otherwise destroy the member 10 by carbonizationof the surface from leakage currents.

In order that any exposed portion of the member 10 will not carryleakage current, a conducting jumper 24 connects the head 11electrically with the flange 22. In very severe conditions where thereis some danger that electrical discharge due to lightning may take placeover the surface of the insulator, the gripping head 11 may be providedwith discharge members 25 which may be in the form of extensions of thebars 16. These discharge members, in addition to providing a path forthe discharge between these points, also tend to grade the electricalstress at the ends Iof the insulator and provide an improved operatingcondition.

In the form of the invention shown in Figs. 5 and 6, the central stressmember 26 is cylindrical and is spread at its end by a wedge 27 seatingit firmly in a collar 28 having a tapered opening therein. A fitting 29is secured to the collar 28 by cap screws 30 and holds the wedge 27 inplace. The sleeve 31 and packing members 32, 33 and 34 are circu-- larin section but are otherwise similar to the corresponding members inFig. 1.

Figs. 7, 8, 9 and 10 show another modification of the insulator intendedfor more severe conditons or higher operating voltages. The insulatingsleeve 35 is provided lwith flanges 36 and an expansion chamber 37,which is attached to the sleeve 35, so as to provide means for keepingthe f space 38 filled with compound or insulating material at all times.This expansion chamber may be located at any position along thesleeve 35but its location may differ for different positions of the insulator inuse.

Where an expansion chamber is provided, it is possible to use a softcompound or insulating oil, the expansion chamber taking up anyvariations in volumetric expansion or contraction in the tension member,in the In Fig. 7 the compound, or in the sleeve. flange 39 secured tothe sleeve 35 is provided with discharge or flux horns 40 instead of thehead at the end of the stress member. The packing material 41 iscompressed in a pocket formed about the stress member 10 by an extension42 of the flange 39. With this arrangement, it is not necessary toprovide a special gland or pocket in the sleeve 85. The other parts aresimilar to those of Fig. 1. In this vform of the invention, a shorterportion of the tension member 10 is exposed outside of the cover sleeve35 than in the form shown in Fig. l. The exposed wood portion ispreferably thoroughl impregnated with a weatherproofing an preservingcompound.

It is evident that many modifications may be provided. The improvedconstruction provides an insulator having a tension member equipped witha weather jacket and a cheaper means for insuring a tight seal betweenthe weather jacket or its attachments and the tension member. With thismethod of construction, it is possible to provide insulators forpractically any mechanical load and having high insulation and smallsize. The method of construction permits of a lower cost so thatinsulators of this type are available for many purposes where the costof former types was prohibitive. Where the conditions are severe, it isusually advisable to impregnate thoroughly or varnish the tensionmembers 10 where the latter are made of wood. Where the cores of thewood are filled with an insulating varnish, the capillary attractionwill prevent moisture being carried into the inside of the sleeve.

I claim 1. An insulator comprising a porcelain tube, a wood barextending through said tube, a gripper head of conducting materialsecured to the projecting end of said bar, a metal flange secured to theend of said tube and insulated from said gripper head by the end portionof said wood bar, means attached to said flange for forming a packedjoint between the end of said tube and said bar, and a jumper connectingsaid gripper head and fiange.

2. An insulator comprising a dielectric tubular member, a fibre rodextending through said member, a gripper head of conducting materialsecured to the end of said rod and spaced from the end of said tubularmember, means forming a pocket at the end of said member around saidfibre rod, a flange of conducting material secured to the end of saidtubular member, packing disposed in said pocket against the surface ofsaid rod, means attached to said flange for pressing said packing intosaid pocket and against the surface of said rod, and a umper bridgingthe space between ,said gripper head and said iange.

3. An insulator comprising a dielectric tube of weather resistingmaterial, a wood bar extending through said tube and projecting from theend thereof, a holding member of conducting material secured to the endof said wood bar, means for forming a packed joint between the end ofsaid dielectric tube and the surface of said wood bar at a point spacedfrom said holding member, means electrically connecting said holdingmember and the surface of said dielectric member, and a discharge hornelectrically connected with said holding member and extending therefromtoward the opposite end of said insulator and spaced outwardly from saiddielectric tube.

4. An insulator comprising a stress member of fibrous material having aslot formed in the end thereof, a friction plate disposed in said slot,wedge shaped friction plates engaging opposite faces of said stressmember, holding members having faces inclined toward each other engagingthe outer faces of said friction plates, and a bolt extending throughsaid holding members, wedge shaped plates, friction plate and stressmember for holding said parts together' and pressing said wedge shapedplates and friction plate into frietional engagement with said stressmember.

An insulator comprising a porcelain tube, a wood bar extending throughsaid tube, a gripper head of conducting ma- `terial secured to theprojecting end of said wood bar, .c packed joint between said porcelaintube and the surface of said wood bar at a point spaced from saidgripper head, means electrically connecting said gripper head and thesurface of said porcelain tube, and a dis- Charge horn electricallyconnected with said gripper head and extending toward the end of saidinsulator opposite said gripper head.

6. An insulator comprising a wood bar having flat faces at the sidesthereof, wedge shaped metallic members engaging said faces, clampingplates having inner faces dis posed at an oblique angle to each otherand engaging the outer faces of said wedge shaped members the outerfaces of said clamping plates being also at an oblique angle to eachother, and a bolt extending through said clamping plates, wedge shapedmembers and bar said bolt being bent to bring the axis of said bolt atthe ends thereof normal to the outer faces of said clamping platesrespectively.

7. An insulator comprising an insulating stress bar of material subjectto injury by passage of leakage currents over the surface thereof, aninsulating casing for the central portion of said bar supported at itsends upon said bar at points spaced inwardly from the ends of said bar,means for forming tight joints at the ends of said casing between saidcasing and the lateral surface of said bar, holding members att-ached tothe ends of said bar beyond the ends of said casing leaving portions ofsaid bar exposed, and electrical conductors bridging the space betweensaid holding members and the ends of said casing.

8. An4 insulator comprising a wood bar, a

' the ends of said tube.

9. An insulator comprisingv a tension bar of fibrous insulatingmaterial, a housing of refractory insulating material surrounding saidbar, the ends of said bar projecting from the opposite ends of saidhousing, holders of conducting material secured to the projecting endsof said bar beyond the ends of said housing, electrical conductorsbridging the space between said holders and the surface of said housing,and arcing horns electrically connected with said holders respectivelyand lxtended toward the middle portion of said 10. A strain insulatorcomprising a wood bar having the end thereof slotted, a fitting for saidinsulator comprising a friction plate disposed in the slot in said barand clamping plates at opposite sides of said bar, a bolt extendingthrough said friction plate, clamping plates and bar for holding saidfitting in place on said bar, said fitting comprising means forming awedging connection with said bar to tighten the grip of said fitting onsaid bar when tension is exerted on said bar, said clamping plates beingbent intermediate the ends thereof and inclined inwardly at oppositesides of the bent portions of said plates, said bolt being bent todispose the heads thereof squarely against the outer faces of saidclamping plates.

11. A wood strain insulator comprising a wood bar having the end thereofslotted forming tongues, a fitting for said bar for gripping thetongues, said fitting comprising a friction plate disposed in the slotbetween the tongues, clamping plates at opposite sides of the bar andhaving relatively converging outer faces wedging means disposed in thespace between said clamping plates and cooperating with said clampingplates and said friction plate to produce a gripping action on saidtongues, and a bolt passing through openings in said tongues, frictionplate and clamping plates, certain of said openings being larger thansaid bolt to permit slipping of said bar in said fitting to tighten thewedging grip on said tongues, said bolt being bent to position the headsthereof squarely against the faces of said clamping plates.

12. An insulator comprising a wood stress member and a holding member,said members having overlappingv interfitting friction plates, a boltpassing through perforations in said plates for pressing said plates t0-gether, the perforations in the plates of one of said members havingsufficient clearance to permit relative slipping of said plates understress of a load on said insulator, and a wedge registering withoverlapping portions of said plates for forcing said plates more tightlytogether when they slip under load. 13. An insulator comprising a woodstress member slotted at its end to provide wood friction plates,holding means comprising' a metallic friction plate extending betweenthe wood plates of said-stress member, clamping plates disposed outsideof said friction plates and having clamping surfaces inclined relativeto each other, a bolt passing through perforations in said plates tohold said plates together, said bolt having clearance in all of the`said plates fixed to one of said members to permit relative slippingunder load of the plates fixed to said respective members, and a wedgebearing on some of said plates and having wedging surfaces inclined in adirection to increase the pressure between said plates when said platesslip under load.

14. An insulator comprising a wood stress member slotted at its end toprovide wood friction plates, a holding member comprising a metallicfriction plate extending between the wood plates of said stress member,clamping plates disposed outside of said friction plates, a bolt passingthrough perforations in said plates to hold said plates together, saidbolt having clearance in all of the said plates fixed to one of saidmembers to permit relative slipping under load of the plates fixed tosaid respective members, and a wedge bearing on said plates and havingits wedging surfaces inclined in a direction to increase the pressurebetween said plates when said plates slip under load, said clampingplates having their outer faces inclined to correspond to theinclination of the surface of said wedge, said bolt being bent todispose the head thereof squarely against the outer faces of said.clamping plates.

15. In an insulator, a wood stress member having the end thereof slottedto provide frictional surfaces and holding means for said stress member,said holding means comprising a friction plate disposed in a slot insaid stress member, clamping plates disposed outside of the outer facesof said stress mem- -ber and pressing the slotted portion of said sionon said insulator increases the gripping action on said stress member,and a bolt extending through said clamping plates, saidl stress memberand said friction plate for holding said parts together, said bolt beingbent to dispose the heads of said bolt squarely against the inclinedfaces of the clamping plates.

In testimony whereof I have signed my name to this specification this12th day of September, A. D. 1928.

ARTHUR O. AUSTIN.

